1. Field of the Invention
The present invention relates to a photometric method and apparatus for cameras, capable of dividing a field to be photographed into a plurality of regions which are in turn metered in a photometric manner with the resulting outputs being used to operate a proper exposure on the entire field.
2. Description of the Prior Art
Commercially available cameras are of such a type as controlled only by a single photometric output. Thus, these cameras are subject to a certain light such that a proper exposure will be hard to obtain under a specific source of light such as rear light, spot-like light or others. To overcome such a problem, various attempts have been made in which a field to be photographed is divided into a plurality of regions which are in turn metered in a photometric manner. Applicant has proposed several attempts in U.S. Pat. Nos. 4,412,730 and 4,306,787. Particularly, the latter provides a practical process in which marginal, photometric outputs are compensated by signals from a lens to eliminate effects such as Vignetting and others such that a proper exposure can positively be determined. However, one must consider the properties of various different lenses which are actually utilized when the above process is carried out.
Compensation for marginal amount of light depends on the property of a lens used. Amount to be compensated in the telephoto lens is different from that in the wide-angle lens in the order of one step. If an exposure is computed without consideration of such a difference, the result would be erroneous.
Furthermore, when photometry processing is controlled in accordance with detected focal length of a phototaking lens mounted on the camera body, a problem may arise in determining the appropriate shutter speed program if a teleconversion lens is used together with the phototaking lens.